Fat bloom is the development of crystals of unstable fat on the surface of chocolate and vegetable fat coatings on storage. In some circumstances, bloom will also form on milk chocolate. Although bloom is detrimental to the appearance of the chocolate, it does not harm its eating qualities. Certain fats when added to chocolate can inhibit bloom formation, the best known being butter oil. The best protection is obtained by adding about 4% butter oil to the chocolate but such a relatively large amount has an appreciable softening effect on the chocolate which tends to lose its snap. However, the anti-bloom effect of butter oil does not apply to vegetable-fat coatings such as lauric fat coatings, e.g. stearines. Other fatty materials have been tried but generally they have not been completely satisfactory.